In September of 1984, I put forward a new idea-converting water wells into gas wells. But at that time, few geologists and engineers accepted it.
Many successful cases, however, have repeatedly proven the new way for exploiting natural gas. In 1986, one of the abandoned water wells in Sichuan basin, People's Republic of China, was first put into testing and was successfully turned into a gas well by using water drainage.
Since then, tens of abandoned water wells have been converted into commercial gas wells. The highest gas yield for single wells is 7 million cu m/day. The petroleum companies involved have benefited greatly from this new, unconventional method in the production of natural gas.
From 1876 to 1985, the US Department of Energy organized an industrial test of 13 water wells for exploiting dissolved gas from geopressured aquifers on the Gulf Coast. However, they did not achieve expected results due to the high production cost.
Based on my experiences and a detailed examination of the geological conditions of the Gulf of Mexico basin, I feel certain that a portion of more than 1,000 water wells (water intervals) there can be converted into gas wells, and thus a great deal of gas reserves can be discovered.
The gas reserves of a big, dynamic system could be more than 70 billion cu m, and the highest gas yield may exceed 7 million cu m/day. Here are the major reasons:
- Geopressured aquifers are very rich in free gas. There could be more than 35 trillion cu m in the Gulf of Mexico basin itself.
- Compartmentalized geopressured aquifers isolated from each other are convenient for water discharge. The yield of a single water well is usually more than 500 cu m/day, which can speed up the process of discharging.
- The dissolved gas can facilitate water drainage, and it is a byproduct decreasing the cost of discharge.
- Many exhausted gas wells can be used to receive the discharge water, and therefore prevent slumping the ground or field.
- Currently, there is a great demand for natural gas.
I believe that this new, unconventional way for exploiting natural gas will play an important role in the natural gas industries, and the companies involved will benefit greatly from it. In addition, the new way for exploiting gas may well be applicable to other oil and gas basins, such as Great Valley-Francisco Geosynclinal area, Mississippi Salt basin, Anadarko-Ardmore basin, Delaware basin, and Green River basin.
Now is the time to exploit the free gas from the geopressured aquifers. The key is how to select water wells that could be converted into gas wells.
Understanding the geological data for the surrounding area is required in addition to analyzing the water well itself.
Bibliography
Chen Liguan, Zhang ChangSheng, et al., "Trying to Demonstrate the New Way for Finding Gas Pools in Yangxin Series of Permian of Southern Sichuan-Finding Gas by Water Withdrawal," Matira; Natural Gas Industry, 1986, vol. 6, No.3, pp. 35-41 (published in People's Republic of China).
Swanson, R.K., Bernard, W.J., and Osoba, J.S., "A Summary of the Geothermal and Methane Production of US Gulf Coast Geopressured Zones from Test Well Data," JPT, December 1986, pp. 1365-70.
Liguan Chen
President
C&C Consultants Ltd.
Calgary
